Hi Beata!,
With modeling chocolate you can begin your work earlier, and just leave it in a cool room, no refrigeration necessary. The chocolate will stick to the copper on it’s own, but you could put a thin coat of piping gel on if you wanted. You may have seen it, but here is a link to my WOW stein, the alternate picture shows the copper armature I made to do it. Not nearly as complicated as the dragons, but still the same concept
Jenniffer White, Cup a Dee Cakes - http://cupadeecakes.blogspot.com